Operations

Operations since the last newsletter have remained largely trouble free, with the exception of wind - it has been a particularly windy period recently, with a record-breaking 59.6 hours lost time logged in January alone.

Methanol multibeam receiver

The seven-beam methanol multibeam receiver was delivered and successfully installed on the 64-metre dish in the week of 16 January 2006, with the first users, the Galactic Methanol Maser Survey team (P502), up and running on the following weekend (see separate reports). The receiver is performing well, with more than 50 new maser detections in the first survey session of nine days observing. Science results have already begun to flow - see e.g. the Parkes home page at www.parkes.atnf.csiro.au and the cover article in this newsletter.

Grahame Moorey, Pat Sykes, Les Reilly and Paul Doherty from Marsfield worked tirelessly alongside local staff Brett Dawson, Ken Reeves and Jeffrey Vera to ensure the installation was effected as smoothly as possible (see separate report).

The receiver appears to be performing to all specifications although analysis of the commissioning tests is not complete at the time of writing. It has two independently-tunable conversion chains, which in principle allow full dual-frequency operation. At the present time only six beams out of the full seven on the second frequency can be used, owing to limitations in the downstream signal processing. It is expected that the full seven beams will be operational on both frequencies for both spectral line and pulsar observing sometime during the 06APRS term.

The next large project to use the receiver will be the Methanol Multibeam Pulsar Survey (P512), which will shortly commence a new high frequency survey of pulsars in the Galactic plane.

Backends

The prototype Digital Filterbank (DFB) continues to work extremely well for pulsar timing observations, and has recently been used with great success for an entirely different purpose - broadband continuum polarimetry mapping. A new configuration has been provided that produces all three polarisation products (AA* BB* and AB*) at a fixed one second time resolution (other periods also may be possible on request). This configuration was successfully used in January by the Parkes Galactic Meridian Survey team at 2.3 GHz to produce images of diffuse Galactic emission in full Stokes parameters. The bandwidth of the DFB is currently restricted to 256 MHz.

Previous attempts at polarised continuum imaging over the last 18 months using the Wideband Correlator (WBC) have struck difficulties with low-level artefacts in the cross-product, which appear to arise in the Wideband Correlator itself.

Plans for the full version of the Digital Filterbank are currently on hold, as delivery of the Xilinx field programmable gate arrays (FPGAs) required for the project did not materialise as advertised, and remain uncertain.

Upgraded Observatory network access

At the time of writing two Caterpillar bulldozers (a D8 towing a D6) are within a kilometre of the Observatory, laying the fibre connection from the former NextGen backbone 10 kilometres to the West. The backbone itself is now "lit" and currently under test by its new owners, AARNet. It is now anticipated that the Observatory will have a 1 Gbit/s connection to the Marsfield laboratory by mid-March. Thanks go to all those responsible for bringing this landmark development to fruition, particularly to Shaun Amy, Tasso Tzioumis, Andrew Hunt, Brett Preisig and, not least, our colleagues at AARNet who are making this enterprise possible.

The new fibre connection will initially constitute an improvement of three orders of magnitude in data speed in and out of the Observatory (which is currently 512 kbit/s), but bandwidths of 10 Gbit/s or more are now within relatively easy reach, when required.

John Reynolds
Officer-in-Charge, Parkes Observatory
(John.Reynolds@csiro.au)